System and Method for Forming a Container Having a Grip Region

ABSTRACT

A container forming assembly and method includes receiving a parison within a cavity of a mold, enclosing the parison within the mold having a wall with a recess, inflating the parison in the mold to form a blow molded container where the blow molded container has a sidewall, a movable region formed at the recess, and a hinge circumscribing an interface between the sidewall and the movable region, and moving the movable region toward an interior of the blow molded container about the hinge before filling. Furthermore, a method for forming a container includes receiving a parison, enclosing the parison with a mold that includes a cavity, and inflating the parison in said mold to form a blow molded container with a moveable region at the cavity. The method further includes repositioning the moveable region before filling the blow molded container.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 11/399,430filed Apr. 7, 2006, the subject matter of which is hereby incorporatedby reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to a method for blow molding acontainer, and more particularly to a method for blow molding acontainer to be formed with deep-set grips so that the formed containerhas secure grippability along with a good ergonomic feel. The presentinvention also relates generally to forming a blow molded container, andmore particularly to a method for forming a blow molded container thatincreases orientation of material at a region of the blow moldedcontainer.

2. Related Art

One method of manufacturing containers is through a process known asstretch blow molding. In this process, a preformed parison, or preform,is prepared from a thermoplastic material, typically by an injectionmolding process. The preform typically includes a threaded end, whichbecomes the threads of the container. During stretch blow molding, thepreform is positioned between two open blow mold halves. The blow moldhalves close about the preform and cooperate to provide a cavity intowhich the preform is blown to form the container. Once the mold isclosed, a gas is forced into the perform causing it to stretch and totake the shape of the mold as the plastic contacts the mold. Aftermolding, the mold halves open to release the blow molded container.

One problem with stretch blow molding is that stretching of the plasticmaterial may affect the performance of the container at certain areas.While the stretching of the plastic material may not cause problems formost sections of the container, it particularly affects the ability ofthe plastic material to form around a deep protrusion in the mold. Insome applications of container manufacturing, a deep protrusion may berequired to form a particular section of a container. For example, theparticular sections of the container formed by an inset or deepprotrusion may include the dome, sidewalls, and the base of thecontainer. As the plastic contacts the deep protrusion of the mold, theplastic must stretch and flow around the protrusion into a recess.However, the plastic material is less able to flow and stretch aroundthe protrusion because, of the contact friction with the mold surface.Insufficient material distribution at a region, such as at the base, mayaffect the ability of the region to maintain its shape around theprotrusion during hot filling, the strength of the region, or theability of the container to stand on a flat surface.

A lack of definition in the base caused by the inability of the plasticto properly form at a deep protrusion is a particular problem. Whilethis is a particular problem in the base region, similar problems existin other regions of a container where an inset is positioned. As statedpreviously, these other regions formed with an inset or deep protrusioninclude the dome, the sidewalls, etc. of a container. These problems canexist with any forming process, such as blow molding, where materialmust flow around a protrusion of a mold to form an inset region of acontainer. This is particularly true for blow molding processesincluding stretch blow molding, extrusion blow molding and injectionblow molding.

Some containers have deep-set grips on either side of the bottle so thata consumer can easily pick up the filled container with a firm grasp ofhis/her hand. When blowing deep-set grips with known blow moldingprocesses, plastic material becomes trapped in the grip regionsconsequently starving other regions of the container of material. Toaccount for this, the container weight is increased as more material isrequired to be used to ensure that a sufficient amount of material isprovided for all parts of the container. Alternatively, designcompromises are made so that the resultant thinner regions are closer tothe axis of the container causing those regions to be blown with morematerial. However, blowing heavier-containers and the resultant designconstraints do not solve the problem described above.

What is needed is an improved method of forming a container with adeep-set protrusion (e.g., in the base and/or as a grip) that overcomesthe shortcomings of conventional solutions that introduce additionalcosts, molding time, and complexity into the mold setup.

Furthermore, conventionally, a container may be manufactured through aprocess known as blow molding. In blow molding, a parison is received ata blow molding apparatus, and the parison is enclosed by a containermold. The blow molding apparatus inflates the parison by forcing gasinto the parison which causes the parison to stretch and take the shapeof the container mold. Once the parison has taken the shape of thecontainer mold, the blow molding step is complete and the container isremoved from the container mold for further processing.

In some applications of container manufacturing, a deep protrusion maybe required at a particular section of a container, most often at a baseor at a hand grip of the container. Deep protrusions, when located atthe base of the container, are sometimes referred to as “push-ups” sincethe protrusions push up into the interior of the container. However,employing known techniques to manufacture containers with deepprotrusions has various problems. One such problem is the orientation ofthe plastic material around the deep protrusion. Orientation refers tohow closely the molecules in a plastic material are packed together.Orientation of plastic molecules occurs as the plastic materialstretches, and the greater the material stretch, the higher theorientation. As the orientation of the plastic molecules increases, themolecules straighten and may form a crystalline structure. Typically,the higher the crystallinity of the plastic, the greater the rigidity ofthe plastic, which improves the structural integrity of the container.The structural integrity of the container may be important during hotfill processing as the container must be able to withstand the rigors ofhot fill processing.

In a hot fill process, a product is added to the container at anelevated temperature, about 82° C., which can be near the glasstransition temperature of the plastic material, and the container iscapped. During hot fill processing and in the subsequent cooling, thecontainer base may experience roll out, distortion, or deformation thatcan cause the container to lean or become unstable. This problem can bereduced or eliminated by increasing orientation of material in thecontainer base.

During blow molding of a container, gas is forced into a parison whichcauses the parison to inflate and stretch to take the shape of thecontainer mold. However, the parison cools as it contacts the containermold. Cooling of the parison affects its ability to stretch, and thusits ability to orient. While this may not cause problems for mostsections of the container, it particularly affects the orientation ofthe material formed around a deep protrusion. As the parison contactsthe deep protrusion, the parison must flow around the protrusion into arecess. As the parison contacts the protrusion and cools, the parison isless able to flow around the protrusion, which affects the ability ofthe parison to stretch and to orient plastic material at the recess.Insufficient orientation at a region, such as at a base or at a handgrip, may affect the ability of the region to maintain its shape aroundthe protrusion, the strength of the region, or the ability of thecontainer to stand on a flat surface. Cooling of the parison also isknown to create thick amorphous plastic sections around the protrusion,which adds excess plastic material to the container and affects therigidity around the protrusion. The thick amorphous plastic sections addto the weight of the container, and thus the cost.

A known system for manufacturing a blow molded container is described inU.S. Pat. No. 5,255,889 to Collette et al., which is incorporated hereinby reference. In the system described therein, a preform is received andenclosed by a mold chamber, which includes two side movable mold membersand a base mold. In the mold chamber, the base mold member has an upperbase plug with a protrusion that extends upward toward the center of themold chamber. During blow molding, gas is forced into the preform toinflate and stretch the preform material into the shape of the moldchamber. As the preform material reaches the protrusion, the materialstretches around the protrusion into a recess to form a bearing surfaceof the container. Once the container is formed, the mold chamber (thetwo side mold members and the base mold member) opens and releases themolded container. However, the base of the containers generated by thissystem may have limited crystallinity, a build up of amorphousunoriented material, or other problems in the base similar to thosedescribed above due to forcing the preform to stretch around theprotrusion into the recess to form the bearing surface of the container.

Likewise, FIG. 10 illustrates a base assembly 100 for forming acontainer base according to the prior art. The base assembly 100includes a base pedestal 102, a centering pin 120, and a base plug 104,with the base plug 104 being secured to a top surface of the basepedestal 102. The centering pin 120 may be used to secure and positionthe base assembly in a blow molding apparatus (not shown). The base plug104 includes a base mold 106 for forming a container base. The base mold106 includes a protrusion 108 for forming a deep protrusion in thecontainer base, and a surface 110 for forming a bearing surface of thecontainer base.

During blow molding of a parison into a container, the base mold 106forms the parison material into a base of the container. As the parisonmaterial contacts the base mold 106, the parison material stretchesaround the protrusion 108 down to the surface 110 for forming thebearing surface, as indicated by the arrows A and B. However, once theparison contacts the protrusion 108, the parison material begins to cooland the orientation of the parison material is slowed, which causes theformation of thick amorphous plastic sections in the base. The thickamorphous plastic sections affect the rigidity of the base, the abilityof the container to stand on a flat surface, and add to the cost of thecontainer.

What is needed is an improved system for forming a deep protrusion in acontainer that overcomes the shortcomings of conventional solutions.

BRIEF SUMMARY OF THE INVENTION

One aspect of the invention is to create a deep-set grip in a containerthat provides secure grippability along with a good ergonomic feel inthe resultant container. In a preferred embodiment, the deep-set grip isachieved in a manner to maintain the overall container weight at an asminimal a weight as possible, and to allow for a wide range of designapplications.

The invention includes a container forming assembly including a moldhaving a sidewall with a recess, and a method for making the container.

A method according to exemplary embodiments of the invention includesreceiving a parison, enclosing the parison within a mold having a wallwith a recess, inflating the parison into the mold to form a blow moldedcontainer where the blow molded container has a sidewall, a movableregion formed at the recess that extends outward from the container, anda hinge circumscribing an interface between the sidewall and the movableregion, and moving the movable region about the hinge before filling theblow molded container with liquid or other consumable product.

A container forming assembly according to an exemplary embodiment of theinvention forms a container from a parison where the container has atleast one movable gripping region. The container forming assemblyincludes a mold adapted to form a first portion and a second portion ofthe at least one movable gripping region wherein the first portion isrotatable about a first hinge toward an interior of the container, thefirst hinge being formed at a first seam between the first portion andthe container, and said second portion is rotatable about a second hingetoward the interior of the container, the second hinge being formed at asecond seam between the second portion and the container; and a drivemechanism adapted to move the mold to enclose the parison during blowmolding and to release the container after blow molding.

Another exemplary method according to the invention is directed to amethod for increasing crystallinity of a blow molded container. Thisexemplary method includes inflating a parison in a mold having a wallwith a recess to form a blow molded container having a movable grippingregion, the movable gripping region being formed at the recess, the blowmolded container having a hinge coupled to said movable gripping region,the hinge circumscribing an interface between the blow molded containerand the movable gripping region; and moving the movable gripping regionabout said hinge toward an interior of said blow molded container beforefilling the blow molded container.

The container forming assembly according to another exemplary embodimentwould include a first mold half forming a first movable gripping regionand a second mold half forming a second movable gripping region wherethe second movable gripping region has hinges, rotatable portions andthe structure of the first movable gripping region.

In the exemplary embodiment, each of the first and second mold halveshave a recess forming a movable gripping portion forming region thatincludes a first surface adapted to form a first outer grip portion ofthe movable gripping region, a second surface adapted to form a secondouter grip portion of the movable gripping region, a third surfaceadapted to form a first inner grip portion of the movable grippingregion, a fourth surface adapted to form a second inner grip portion ofthe movable grip portion; and a fifth surface area adapted to form aridge area of the movable gripping portion.

The container forming assembly of the foregoing exemplary embodiment mayfurther have its fifth surface area positioned between the third andfourth surfaces, and wherein the third and fourth surfaces positionedadjacent to the first and second surfaces, respectively.

The invention also includes a method for forming a container, a methodfor increasing crystallinity of a container, a base assembly for forminga container, and a container.

The method of the invention for forming a container includes receiving aparison, enclosing the parison with a mold having a cavity, inflatingthe parison in the mold to form a blow molded container with a moveableregion at the cavity, and repositioning the moveable region beforefilling said blow molded container.

The method of the invention for increasing crystallinity of a containerincludes inflating a parison to form a blow molded container having amoveable region, at least a portion of the moveable region protrudingoutward from the blow molded container, and repositioning the moveableregion before filling the blow molded container.

The base assembly of the invention, which is adapted to form a containerwith a base having a moveable region and having a bearing surface,includes a base pedestal, a push rod coupled to the base pedestal, and abase plug coupled to the base pedestal. The base plug has a base moldadapted to form the moveable region and to from the bearing surface ofthe base so that at least a portion of the moveable region protrudesoutward from the base beyond the bearing surface. The push rod isadapted to reposition the moveable region before filling the container.

The container of the invention includes a base having a moveable regionwith a dimple, and a bearing surface that is offset from the moveableregion. After blow molding and before filling the container, at least aportion of the moveable region protrudes outward beyond the bearingsurface.

Further advantages, as well as the structure and function of exemplaryembodiments will become apparent from a consideration of thedescription, drawings, and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following, more particular description of exemplaryembodiments of the invention, as illustrated in the accompanyingdrawings, wherein like reference numbers may generally indicateidentical, functionally similar, and/or structurally similar elements.

FIG. 1 depicts an exemplary embodiment of a first stage of a containerwith the deep-set grip inverted, according to the present invention;

FIG. 2 depicts a cross sectional view of the exemplary container of FIG.1 according to the present invention;

FIGS. 3A-B depict an exemplary embodiment inverting a grip of acontainer according to the present invention;

FIG. 4 illustrates a parison received before a mold according to anexemplary embodiment of the invention;

FIG. 5 schematically illustrates an exemplary blow molded container witha movable region according to the invention;

FIG. 6 schematically illustrates another exemplary blow molded containerwith a movable region being inverted prior to release from the mold-oneach side of the container;

FIGS. 7A-C schematically illustrate the movable region of the exemplarycontainer being inverted after release from the mold;

FIG. 8 illustrates a mold for forming half of the container shown inFIG. 1; and

FIG. 9 shows an embodiment of the mold that can be activated to push inan outwardly protruding region toward the center of the container.

FIG. 10 illustrates a base assembly for forming a container baseaccording to the prior art.

FIGS. 11A-11D illustrate an exemplary embodiment of a base assemblyaccording to the present invention.

FIGS. 12A-12B illustrate an exemplary embodiment of using a baseassembly to form a container base according to the present invention.

FIGS. 13A-13B illustrate exemplary embodiments of a push rodrepositioning the container base according to the present invention.

FIGS. 14A-14B illustrate an exemplary embodiment of a container prior toand after repositioning according to the present invention.

Further objectives and advantages, as well as the structure and functionof exemplary embodiments will become apparent from a consideration ofthe description, drawings, and examples.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the invention are discussed in detail below. Indescribing the exemplary embodiments, specific terminology is employedfor the sake of clarity. However, the invention is not intended to belimited to the specific terminology so selected. While specificexemplary embodiments are discussed, it should be understood that thisis done for illustration purposes only. A person skilled in the relevantart will recognize that other components and configurations may be usedwithout parting from the spirit and scope of the invention. Allreferences cited herein are incorporated by reference as if each hadbeen individually incorporated.

Exemplary embodiments of the present invention may generally relate to acontainer, a method of inverting a grip of a container, and a blowmolding apparatus for forming a container having an invertible grip. Inan exemplary embodiment, as shown in FIG. 4, a blow-molding apparatus 10may receive a parison 12 and enclose the parison with a mold 14 a-c,which may include a recess 16 in the outer surface of the mold 14 b. Theblow-molding apparatus 10 may inflate the parison into the mold to forma blow molded container 100 (see FIG. 5). The blowmolded container 100may have a sidewall, a movable region 18 formed at the recess 16, and ahinge circumscribing an interface between the sidewall of container 100and the movable region 18. The blow-molding apparatus may be adapted tomove the movable region 18 about the hinge before filling the blowmolded container 100. An internal volume of the blow molded containermay be reduced by moving the movable region 18 into the center of thecontainer 100 (arrow 22 in FIGS. 6 and 7A) as schematically shown inFIG. 7C. The movable region 18 may form a grip for the container 100. Byblow molding the movable region 18 or grip in its outward position(outside the container) and then inverting the movable region to formthe grip by using a simple mechanical force, the weight of the containermay be reduced and the definition of the grip may be improved.

FIG. 1 illustrates an exemplary embodiment of a container representingthe shape of the container as stretch blow molded according to thepresent invention, FIG. 2 illustrates an exemplary embodiment of amovable region of a container in its outwardly blown position accordingto the present invention, and FIGS. 3A-B illustrate an exemplaryembodiment of the movable region of a container in its outwardly blownposition and the final configuration of the grip according to thepresent invention, respectively.

The exemplary embodiments will initially be discussed with reference toFIGS. 1-2. According to an exemplary embodiment of the presentinvention, container 100 is blow molded into the shape as schematicallyillustrated in FIG. 7. FIG. 1 illustrates a perspective side view of theexemplary container 100 according to an exemplary embodiment of thepresent invention. As depicted, the container 100 includes an upperportion 102, a shoulder 104, a container body 106, and a base 108. Theupper portion 102 of the container 100 generally is any structure havingan opening into the interior of the container 100 and being adapted toreceive a closure (not shown). The closure may be any device used tocreate a substantially air tight seal for a hot-filled product withinthe container 100, thus substantially preventing air from entering thecontainer 100 through the upper portion 102. In one exemplaryembodiment, the upper portion 102 includes threads 112 that are adaptedto couple with a closure that is a twist-on cap. The cap may be twistedonto the threads 112 of the upper portion 102 to create a seal with thecontainer 100. In an alternative embodiment, a sealing plug may beplaced in the upper portion 102 to seal the container 100. Otherclosures or seals may be used, as will be appreciated by those of skillin the art.

The shoulder 1.04 of the container 100 extends from the top of thecontainer body i 06 to the bottom of the upper portion 102. Generally,the shoulder 104 narrows as it progresses from the container body 106 tothe bottom of the upper portion 102. The shoulder 104 may have anydesired shape, or may be omitted from the container 100. The shoulder104 may' include patterns, shapes, and other geometries, oralternatively, may be substantially smooth. In the depicted embodiment,the width of the bottom of the shoulder 104 corresponds to the width ofthe top of the container body 106, and narrows by curving inward as theshoulder 104 approaches the upper portion 102. The shoulder 104 curvesoutward before reaching the upper portion 102, and then curves inward asthe shoulder 104 reaches the upper portion 102. The shoulder 104 may beother shapes and include other patterns, as will be appreciated by thoseof skill in the art.

The container body 106 of the container 100 extends from the base 108 tothe shoulder 104 and defines an interior of the container 100. Thecontainer body 106 is positioned below the shoulder 104. In analternative embodiment, if the shoulder 104 is omitted from thecontainer 100, the container body 106 extends to the upper portion 102.The container body 106 may be any asymmetrical or symmetrical shape,such as, but not limited to, cylindrical, square, rectangular, or othergeometries. Optionally, the container body 106 of the container 100 mayinclude patterned support structure or vacuum panels. The patternedsupport structure and the vacuum panels may help provide structuralintegrity for the container 100.

In the depicted embodiment, the container body 106 has ribs 112positioned at various locations on the container 100. The ribs 112 maybe a series of recessed sections alternating with non-recessed sectionson the container body 106. The ribs 112 may include other types andshapes and may also be placed at alternate locations on the containerbody 106, as will be appreciated by those of skill in the art. The ribs112 may also be omitted from the container body 106, or may be placed atother locations on the container 100.

The container body 106 may also include a movable region 110 thatinitially is blow molded outside of the container 100 (see FIG. 6). Themovable region 110 is comprised of a number of surfaces in the grip areaof the container body 106. The number of surfaces are arranged in a wayso that an external force (arrow 22) acting on the grip area causes thesurfaces to fold in relation to one another until such a point wherethey snap into an inverted position toward the interior of the container100. As depicted in FIG. 2, the movable region 110 may include a firsthinge or seam 202, a first portion 204, a first inner wall 206, a secondhinge or seam 214, a second portion 212, a second inner wall 210, athird hinge or seam 208, a fourth hinge or seam 216, and a fifth hingeor seam 218. The first hinge or seam 202 couples the first portion 204so that portion 204 of the container body 106 is initially blow moldedoutside the container body 106 and then can be pushed inside thecontainer as shown in FIGS. 3A-B, respectively. The second hinge or seam214 couples the second portion 212 so that second portion 212 can bepushed inside the container 106 by pivoting about second hinge or seam214. The fifth hinge or seam 218 couples the first portion 204 with thefirst inner wall 206, and the fourth hinge or seam 216 couples thesecond portion 212 with the second inner wall 210 so that these portionscan be pushed inside container 106. The inverted movable region 110 isshown in FIG. 3B.

The mold of the container forming assembly shown in FIGS. 4-6 may bemade of first and second mold halves 14 a, 14 b that each may include awall with a recess to form respective first and second movable grippingregions 110. The gripping-regions 110 are initially blown outside thecontainer and then inverted so that a consumer's hand easily fits intothe inverted gripping regions.

Initially, when the container 100 is blow molded, the movable region 110is formed extending away from the interior of the container 100. FIG. 3Aillustrates the movable region 110 as blow molded extending away fromthe interior of the container 100, and FIG. 3B illustrates the movableregion 110 extending toward the interior of the container 100 afterinversion. During inversion, a force may be applied to cause the movableregion 110 to invert. As the −force is applied, the first portion 204rotates about the first hinge or seam 202 and the second portion 212rotates about the second hinge or seam 214. Additionally, the firstportion 204 rotates about the fifth hinge or seam 218 relative to thefirst inner wall 206, the second portion 212 rotates about the fourthhinge or seam 216 relative to the second inner wall 210, and the firstinner wall 206 rotates about the third hinge or seam 208 relative to thesecond inner wall 210. That is, a many sided movable region 110 isinitially blown outside the container thereby avoiding the need for amold with a deep-set protrusion around which plastic material hasdifficulty forming the desired thickness about the protrusion. Then, theweights of the plastic at the hinges or seams along with the angles ofthe first and second portions and the inner walls are designed so thatmovable region 110 can be inverted into the container to form a deep-setgrip(s) that a consumer can securely grip and that has a good ergonomicfeel to the consumer. The container wall thickness at the hinges isthinner than the surrounding portions or inner walls, which are heavieras the plastic naturally moves in this manner. The angles of the firstand second portions and the inner walls should be sufficiently steep sothat the desired depth of a grip is achieved and the desired ergonomicfeel.

During inversion, a sufficient force may be applied to the movableregion 110 formed outside the container while the container 100 remainswithin the mold 14 a-c (see FIG. 5). As the Assignee of the presentinvention has successfully inverted projections blown outside the baseof the container, enough force needs to be applied to the movable region110 to cause inversion. In one embodiment, the inversion of the moveableregion 18 (110 in FIGS. 1-3B) may occur as late into the blowing processas possible so that the container 100 is allowed to cool as muchpossible before the container 100 is released or ejected from the mold.The longer the container and movable region can cool, a better inversionresult can be achieved. This is because the warmer the container isduring inversion, the higher the probability that the container willcrease at an undesired location resulting in an aesthetically unpleasingcontainer and thus, a rejected container. The inversion may occur justbefore the container is ejected or released from the mold to reduce thelikelihood that the inversion will form unwanted creases or deformitiesin the container 100. An air cylinder (not shown) may be used for theinversion of the movable region 110 by applying a force to the firstportion 204 and to second inner wall 210. Alternatively, othermechanical, pneumatic, hydraulic, or cam operated means for invertingmay be used, as will be appreciated by those skilled in the art. Forexample, the cam operated means may be included within the mold and themovable region may be inverted while the mold fully encloses the formedcontainer.

The container 100 is blow molded into the shape depicted in FIG. 3A toavoid trapping material in recessed areas of a complex shaped mold andto improve the performance (less rejected containers) of the container100 at the movable region 110 without increasing the amount of materialto the region. The movable region 110 is formed into the shape shown inFIG. 3A to ensure that all surfaces of the movable region are properlyformed with sufficient amounts of material and have sufficientdefinition. An advantage of forming the movable region 110 extendingaway from the interior of the container is that the rigidity at themovable region 110 is increased by allowing for further orientation ofplastic material during the blow molding process (see FIGS. 1, 2, and3A), as compared with initially forming the container with a deep-setprotrusion extending toward the interior of the container (see FIG. 3B).By having the movable region 110 extend away from the interior of thecontainer 100, the orientation of plastic material in the movable region110 is increased since the mold would not trap material, but would allowthe plastic material to further stretch into a cavity of a mold to formthe movable region 110 during blow molding. As the orientation of theplastic molecules increases, the molecules straighten and may form acrystalline structure. Typically, the higher the crystallinity of theplastic, the greater the rigidity of the plastic, which improves thestructural integrity of the container 100 at the movable region 110. Asimilar process for increasing orientation is also described inco-pending U.S. Provisional Utility Patent Application No. 60/671,459,filed Apr. 15, 2005, the contents of which are incorporated herein byreference in their entirety.

It is noted that if the container 100 would be initially blow moldedinto the shape depicted in FIG. 3B, the movable region 110 would not befully formed at the region near the first hinge or seam 202 and near thesecond hinge or seam 212. This is the result of forming a container withthe stretch blow molding technique. As a container is being stretch blowmolded, gas stretches plastic material against a mold for the container,such as a mold for the container 100. If the mold contains a protrusionto form the movable region depicted in FIG. 3B, the plastic materialwould have to stretch around the protrusion from third hinge or seam 208down to the region near the first hinge or, seam 202 and near the secondhinge' or seam 212 (see FIG. 3B). The contact with the mold would trapmaterial at the region near the third hinge or seam 208, and not allowthe material to fully form down into the region near the first hinge orseam 202 and near the second hinge or seam 212. Moreover, forming themovable region 110 with such a protrusion would cause plastic to becometrapped at the movable region 110, which may prevent other areas of thecontainer to not have sufficient plastic to properly form those areas.

Stretch blow molding the container 100 into the shape as illustrated inFIGS. 1, 2, and 3B also reduces the wall thickness of the movable region110 and reduces the occurrence of thick amorphous plastic sections nearthe movable region 110, as compared with forming the container with themovable region 110 extending outwardly from the container as depicted inFIG. 3A. This may allow the amount of plastic material present in themovable region 110 to be reduced without detrimentally affectingcontainer performance, and, in some instances, this technique improvesthe performance of the movable region. Likewise, forming the containerinto the shape as illustrated in FIG. 3A may allow a more uniformdistribution of plastic material in the base 108. Moreover, theincreased rigidity may allow for the inversion of the movable region 110without a substantial net distortion of the container body 106.

FIGS. 4-6 schematically illustrate a container forming assembly forforming a container from a parison according to one embodiment of theinvention. The assembly includes a mold 14 a, 14 b, and 14 c that can bedriven by a drive mechanism to enclose parison 12. A container 100 isblown within the closed mold assembly, as shown in FIG. 5. A recess 16may be disposed in a sidewall of mold 14 a and mold 14 b to form a twosided grip for a container. FIG. 8 illustrates one side of the mold 814for forming a container as shown in FIG. 1. In this embodiment each sidemold would include a recess 816 that has a first surface 804 adapted toform a first outer grip portion (204), a second surface 812 adapted toform a second outer grip portion (212), a third surface 806 adapted toform a first inner grip portion (206) adjacent the first outer gripportion (204), a fourth surface 810 adapted to form a second inner gripportion (210), and a fifth surface area 808 adapted to from a ridge area(208) of a movable gripping region 110. The forming assembly may includea first push rod adapted to rotate the first portion 204 of a movableregion 110 about first hinge or seam 202 to invert the movable region sothat it forms a gripping region. A second push rod may be employed tocause the second portion 212 to rotate about hinge or seam 214 to pushboth sides of the resultant gripping regions within container 100 priorto filling the container with food product. As shown in FIG. 9, asection 900 of the recess 816 that corresponds with surfaces 806 and 810and surface area 808 is movable between the inactive position shown inFIG. 8 and the active position shown in FIG. 9.

This system also benefits from requiring less expensive components.While other systems may use complex pneumatic, hydraulic, or camoperated means to push pieces of the mold inward at a specific point inthe blow molding cycle, the exemplary embodiments may use a simplemechanical means of inverting the movable region 110. This reduces thecost, molding time, and complexity of the mold set up as compared withconventional systems.

Thus, the container 100 according to exemplary embodiments of thepresent invention may improve the sufficient rigidity, definition, andperformance of the container 100 at a movable region 110 therebyallowing a container to be formed that uses less plastic whilemaintaining the performance and appearance of the container.

The embodiments and examples discussed herein are non-limiting examples.The shape of the inset are not limited to the examples shown, as themovable region may blown outward in a round or oval forum and, wheninverted, still obtain the same function—decrease the volume of theblown container.

Furthermore, FIGS. 11A-11D illustrate an exemplary embodiment of a baseassembly 200 according to the present invention. FIG. 11A illustrates aside view of the base assembly 200 having a push rod 226. FIG. 11Billustrates a side view of the base assembly 200 with a rod end 212 ofthe push rod 226 extended. FIG. 11C illustrates a top view of the baseassembly 200. FIG. 11D illustrates a cross sectional view of the baseassembly 200 along line A-A of FIG. 11C to further depict the push rod226. In the following description, reference to FIGS. 11A-11D will bemade.

The base assembly 200 includes a base pedestal 202, a base plug 204, acentering pin 220, and a push rod 226. The centering pin 220 may be usedto secure and position the base assembly 200 in a blow molding apparatus(not shown). The base pedestal 202 may have any shape, so long as it hasa hollow central region for receiving the push rod 226, and a top regionadapted to connect with the base plug 204. In an alternative embodiment,the base plug 204 and the base pedestal 202 may be a single apparatus.During blow molding, the base assembly 200 is raised to connect withother mold assemblies for blow molding of a container. After thecontainer is blow molded, the base assembly 200 is lowered to releasethe container.

The push rod 226 is a cylindrically shaped rod that is located above thecentering pin 220 and extends through the base pedestal 202 up to asurface of the base plug 204. In one embodiment, the push rod 226 is ametal mold component. The base assembly 200 includes a mechanism thatmoves the push rod 226 and elevates a rod end 212 of the push rod 226above the surface of the base plug 204. In an alternative embodiment,only the rod end 212 of the push rod 226 may be elevated. The mechanismfor elevating the push rod 226 may be a spring, a cam, or may be drivenpneumatically, hydraulically, or electronically. The mechanism may belocated internal or external to the push rod 226. The rod end 212 isformed at the end of the push rod 226, and the top surface of the rodend 212 is used to form a dimple in the base of the container. The shapeof the rod end 212 is similar to a truncated cone, where the end of thetruncated cone includes a section 218. The section 218 of the rod end212 may be concave, and the section 218 may be adapted to form a convexsection in the base of the container that extends downward away from thecenter of the container. In alternative embodiments, the section 218 ofthe rod end 212 may be flat or convex extending upward toward the centerof the container. The section 218 is used to reposition a moveableregion of the base from an initially outward protruding position to aposition within the container cavity, as will be discussed later indetail.

The base plug 204 includes a base mold 206 having a contact surface 208adapted to contact a parison material during blow molding of acontainer. The contact surface 208 of the base mold 206 forms the shapeof the base of the container. The contact surface 208 is a curvilinearmold for forming a moveable region and a bearing surface of a containerbase. As will be described later in detail, once the base of the bottleis formed, the moveable region of the base is repositioned from anoutwardly protruding position toward the interior of the container. Inone embodiment, the movable region is repositioned to a position withinthe interior of the container, thus forming a container base that isstructurally and functionally similar to that of a container having aconventional push up.

The contact surface 208 includes a cavity 210, a surface 214, and asurface of the rod end 212. The surface of the cavity 210 and thesurface of the rod end 212 form an inner region 220 of the base mold206, and the surface 214 forms an outer region 222 of the base mold 206,with the outer region 222 being offset from the inner region 220. Theinner region 220 and the outer region 222 are adapted to form a base ofa container during blow molding. The outer region 222 is substantiallyflat and is adapted to form a bearing surface of a container. In analternative embodiment, the outer region 222 may be non-flat or rounded,or may form a discontinuous bearing surface. The present invention canthus be adapted to form bearing surfaces with geometries known in theart.

When viewing a side cross section of the mold 206, the cavity 210 is adepression in the base mold 206 that is adapted to form a moveableregion in a container. The cavity 210 begins at the outermost edge ofthe inner region 220, and curves both inward toward the center of thebase mold 206 and downward toward the bottom of the base assembly 200.Prior to reaching the rod end 212, the cavity 210 reaches its bottom andbegins to curve upward. From the bottom of the cavity 210, the cavity210 curves both inward toward the center of the base mold 206 and upwardaway from the bottom of the base assembly 200. The cavity 210 ends atthe truncated end of the rod end 212. In an alternative embodiment, thebottom of the rod end 212 may occur at other locations in the base mold206 relative to the rod end 212, or may even be positioned on the rodend 212. When the base mold 206 is viewed from the top, the cavity 210is a circular depression in the base mold 206 (see FIG. 11C). The cavity210 is located between the outermost edge of the inner region 220 andthe outermost edge of section 218 of the rod end 212. In an alternativeembodiment, the cavity 210 may be any symmetric or asymmetric shapeother than a circular depression. For example, the cavity may form atriangle, a rectangle, or a polygon. In a further alternativeembodiment, the cavity 210 does not curve upward from its bottom, andinstead may curve further downward or may be flat until it reaches thecenter of the base mold 206.

FIGS. 12A-12B illustrate an exemplary embodiment using a base assembly200 to form a base of a container according to the present invention. InFIG. 12A, a parison 304 having a threaded finish is attached to a holder302 of a blow molding apparatus (not shown) that is adapted to form ablow molded container. Surrounding the parison 304 is a first side mold306, a second side mold 308, and the base assembly 200. The first sidemold 306 contains a mold of one side of the container, and the secondside mold 308 contains a mold of the other side. The first side mold 306and the second side mold 308 may be mirror images of one another, orthey may have different shapes. Other combinations and different numbersof molds may be used, as is understood by those of skill in the art.

Prior to blow molding, the parison 304 is enclosed by the first sidemold 306, the second side mold 308, and the base mold 206. Asillustrated in FIG. 12B, once the parison is enclosed, gas is forcedinto the parison 304 to inflate the parison 304 in the first side mold306, the second side mold 308, and the base mold 206. During inflation,the parison 304 stretches into the form of the first side mold 306, thesecond side mold 308, and the base mold 206. As the parison materialcontacts the base mold 206, the parison material is blown against thecontact surface 208 into the cavity 210. The parison material stretchesinto the cavity 210 to form a moveable region in the base of thecontainer.

By having the cavity 210 in the base mold 206, the parison material doesnot encounter a deep protrusion, which would cause cooling and wouldreduce plastic material orientation. Stretching the parison materialduring inflation into the cavity 210, as opposed to around a protrusion,allows the parison material to further stretch and orient since theparison material is blown into a wider space as compared with a narrowrecess around a deep protrusion. The additional stretch increases thecrystallinity of the molecules of the parison material, which increasesthe rigidity of the base and improves the structural integrity of thebase. Blow molding the parison material into the cavity 210 also reducesthe wall thickness of the base and reduces the occurrence of thickamorphous plastic sections in the base. Thus, the amount of plasticmaterial present in the base can be reduced without detrimentallyaffecting container performance, and, in some instances, this techniqueimproves the performance of the base.

FIG. 13A illustrates an exemplary embodiment of the push rod 226repositioning the base of the container according to the presentinvention. In this embodiment, prior to separating the first side mold306, the second side mold 308, and the base assembly 200 from thecontainer, the base of the container is repositioned. After theinflation process of the parison 304 has completed, a base having amoveable region that protrudes outward from the container is formed atthe cavity 210. The moveable region of the container base is downwardlyconvex with respect to a bearing surface, as is described below indetail. The push rod 226 is then elevated upward toward the center ofthe container to elevate the rod end 212 above the contact surface 208to exert pressure on the moveable region of the base. As the rod end 212is further elevated, the moveable region is forced upward toward thecenter of the container into an upward position, which extends inwardinto the interior of the container with respect to the bearing surface.After the moveable region is repositioned upward, the push rod 226 maybe lowered. Thereafter, the first side mold 306, the second side mold308, and the base assembly 200 may release the blow molded container byseparating.

FIG. 13B illustrates an alternative exemplary embodiment of the push rod226 repositioning the base of the container according to the presentinvention. In this embodiment, the base assembly 200 separates from thefirst side mold 306 and the second side mold 308 to release the base ofthe container. Afterwards, the rod end 212 is elevated until it reachesthe moveable region of the container base. The rod end 212 then exertspressure on the base of the container to reposition the moveable regionof the base. Thereafter, the first side mold 306 and the second sidemold 308 may release the blow molded container by separating so that thecontainer may be further processed. In still other embodiments, the baseof the container may be released from the molds without beingrepositioned and sent to a different device for repositioning themoveable region.

FIGS. 14A and 14B illustrate an exemplary embodiment of a container 500prior to and after repositioning by the push rod 206 according to thepresent invention. Prior to repositioning, the base includes a moveableregion 502 and a bearing surface 504, where at least a portion of themoveable region 502 protrudes outward from the base of the containerbeyond the bearing surface 504. The moveable region 502 of the containerbase is downwardly convex with respect to the bearing surface 504.During inflation using base mold 206, the moveable region 502 is formedby the inner region 220 of the base mold 206, and the bearing surface504 is formed by the outer region 222. The moveable region 502 protrudesoutward from an innermost edge of the bearing surface 504 away from thecenter of the container and is downwardly convex with respect to thebearing surface 504. The moveable region 502 is illustrated as beingcircular, but may be any symmetrical or asymmetrical shape. A dimple 518is formed at a center of the moveable region 502 by the surface of therod end 212 of the contact surface 208. The dimple 518 is upwardlyconvex and protrudes inward toward the center of the container 500. Thedimple 518 provides a pocket in which the rod end 212 can be situated asthe push rod 226 extends to reposition the moveable region 502 of thebase.

During repositioning, the moveable region 502 is moved toward the centerinterior of the container by the extension of the rod end 212. In oneembodiment, the moveable region 502 is moved within the interior of thecontainer with respect to the bearing surface 504. In repositioning, therod end 212 contacts the dimple 518 and forces the dimple 518 toward thecenter of the container. This repositions the moveable region 502 andcauses the moveable region 502 to no longer extend or protrude beyondthe bearing surface 504. In an alternative embodiment, the rod end 212may contact the moveable region 502 at other locations to reposition themoveable region 502 of the base, as would be understood by those ofordinary skill in the art. In one embodiment, repositioning of the baseoccurs before the container is filled so that the container may beplaced on a substantially flat surface for transport to, for example, afilling machine, or alternatively, for transport during manufacturing orfor palletizing, as is known in the art. The filling machine may fillthe container by any known filling process, including hot filling, coldfilling, and other filling processes known by those skilled in the art.By repositioning the moveable region 502, the container can stand stablyon a substantially flat surface and be processed similar to containerswith conventionally manufactured push up bases. Thus, the base region,after repositioning the moveable region 502, has the appearance andfunctionality of a conventional blow molded base with a push up, withoutthe disadvantages of the prior art.

The container 500 has a one-piece construction and can be prepared froma monolayer plastic material, such as a polyamide, for example, nylon; apolyolefin such as polyethylene, for example, low density polyethylene(LDPE) or high density polyethylene (HDPE), or polypropylene; apolyester, for example polyethylene terephthalate (PET), polyethylenenaphtalate (PEN); or others, which can also include additives to varythe physical or chemical properties of the material. For example, someplastic resins can be modified to improve the oxygen permeability.Alternatively, the container 500 can be prepared from a multilayerplastic material. The layers can be any plastic material, includingvirgin, recycled and reground material, and can include plastics orother materials with additives to improve physical properties of thecontainer. In addition to the above-mentioned materials, other materialsoften used in multilayer plastic containers include, for example,ethylvinyl alcohol (EVOH) and tie layers or binders to hold togethermaterials that are subject to delamination when used in adjacent layers.A coating may be applied over the monolayer or multilayer material, forexample to introduce oxygen barrier properties.

Although the present embodiment and the figures illustrated the parison304 as a preform having threads at the top, the parison may also be athreadless plastic tube without departing from the scope of theinvention. One example using a parison that is a plastic tube involvesinserting a needle into the parison, and forcing gas through the needleto expand the plastic tube to take the shape of a mold. Additionally,any blow molding technique may be used for forming the container,including injection blow molding, stretch blow molding, or extrusionblow molding, as would be understood by those of skill in the art.

It is noted that the detailed description describes a technique for blowmolding a moveable region 502 on a container base by molding a parisonmaterial into a cavity 210. However, this technique may be used to formother regions of a container other than the base, such as to form atleast a portion of a hand grip of a container, or to form other deepprotrusions of a container. The cavity 210 may also be located on eitherside mold 306 or 308, or on other locations in the base mold 206. Thistechnique is useable on any region of a plastic container where a deepprotrusion is required. The technique described herein increases therigidity of a region having a deep protrusion, while reducing thickamorphous plastic sections around the region caused by the deepprotrusion.

The exemplary embodiments illustrated and discussed in thisspecification are intended only to teach those skilled in the art thebest way known to the inventors to make and use the invention. Nothingin this specification should be considered as limiting the scope of thepresent invention. All examples presented are representative andnon-limiting. The above-described exemplary embodiments of the inventionmaybe modified or varied, without departing from the invention, asappreciated by those skilled in the art in light of the above teachings.It is therefore to be understood that, within the scope of the claimsand their equivalents, the invention may be practiced otherwise than asspecifically described.

1-17. (canceled)
 18. A plastic container comprising: a cylindrical bodydefining a longitudinal axis and having an upper portion, a sidewallportion, and a base portion having a base, the base portion defining aradial sidewall and a central inset portion defined inboard of a thinnedwall portion formed around at least a portion of the base.
 19. Theplastic container of claim 18, wherein the base portion further definesan outer heel portion, the outer heel portion having a wall thicknessgreater than a wall thickness of the thinned wall portion.
 20. Theplastic container of claim 18, wherein the thinned wall portion is acontinuous annular structure around the container base.
 21. The plasticcontainer of claim 18, wherein the thinned wall portion is adiscontinuous annular structure around the container base.
 22. Theplastic container of claim 18, wherein the thinned wall portion is asegmented annular structure around the container base.
 23. The plasticcontainer of claim 18, wherein the plastic container is composed ofpolyethylene terephthalate (PET).
 24. The plastic container of claim 18,wherein the upper portion includes a polyethylene terephthalate (PET)blown finish.
 25. The container of claim 18, wherein the base isconfigured to be physically acted on by a base forming assembly having amovable insert portion.
 26. The container of claim 18, wherein thethinned wall portion is a hinge about which the central inset portion isconfigured to move.
 27. The container of claim 26, wherein the centralinset portion is configured to move about the hinge toward an interiorof the plastic container.
 28. The container of claim 27, wherein anentirety of the central inset portion is at or above a bearing surfaceof the plastic container after being moved about the hinge toward aninterior of the plastic container.
 29. The container of claim 18,wherein the central inset portion includes a movable portion centrallylocated about the longitudinal axis, the movable portion always being ata highest position with respect to a plane running through a bearingsurface of the plastic container, as compared to other portions of thecontainer base.
 30. The container of claim 18, wherein the central insetportion divides a movable portion of the base from a non-movable portionof the base.
 31. The container of claim 18, wherein the container baseis thinned with respect to non-base portions of the plastic container.32. The container of claim 18, wherein the thinned wall portion isconvex in shape and extends into the plastic container.